| 说明 |
时间 |
| 首次发布 |
2017年06月23日 |
| 最近更新 |
2019年09月03日 |
单例手写
// .h
#import <Foundation/Foundation.h>
NS_ASSUME_NONNULL_BEGIN
@interface MZDaoManager : NSObject
+ (instancetype)shareManager;
@end
NS_ASSUME_NONNULL_END
// .m
#import "MZDaoManager.h"
// 1、提供全局变量
static MZDaoManager *_manager = nil;
@implementation MZDaoManager
// 2、alloc/new -> allocWithZone
+ (instancetype)allocWithZone:(struct _NSZone *)zone {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_manager = [super allocWithZone:zone];
if ([_manager respondsToSelector:@selector(initData)]) {
[_manager performSelector:@selector(initData)];
}
});
return _manager;
}
// 3、提供类方法
+ (instancetype)shareManager {
return [[self alloc] init];
}
// 4、严谨：兼容copy和mutableCopy
- (id)copyWithZone:(NSZone *)zone {
return _manager;
}
- (id)mutableCopyWithZone:(NSZone *)zone {
return _manager;
}
// 以下为兼容MRC，由于现在的工程绝大多数都是ARC，故可忽略。
#if !__has_feature(objc_arc)
- (NSUInteger)retainCount {
return MAXFLOAT;
}
- (oneway void)release {}
- (instancetype)retain {
return _manager;
}
#endif
@end
推荐：单例模式通用宏
#ifndef MZSingleInstance_h
#define MZSingleInstance_h
#define MZSingleInstanceH(name) + (instancetype)share##name;
#if __has_feature(objc_arc)
// ARC
#define MZSingleInstanceM(name)\
static id _manager = nil;\
+ (instancetype)allocWithZone:(struct _NSZone *)zone {\
static dispatch_once_t onceToken;\
dispatch_once(&onceToken, ^{\
_manager = [super allocWithZone:zone];\
if ([_manager respondsToSelector:@selector(initData)])\
[_manager performSelector:@selector(initData)];\
});\
return _manager;\
}\
\
+ (instancetype)share##name {\
return [[self alloc] init];\
}\
\
- (id)copyWithZone:(NSZone *)zone {\
return _manager;\
}\
\
- (id)mutableCopyWithZone:(NSZone *)zone {\
return _manager;\
}
#else
// MRC
#define MZSingleInstanceM(name)\
static id _manager = nil;\
+ (instancetype)allocWithZone:(struct _NSZone *)zone {\
static dispatch_once_t onceToken;\
dispatch_once(&onceToken, ^{\
_manager = [super allocWithZone:zone];\
if ([_manager respondsToSelector:@selector(initData)])\
[_manager performSelector:@selector(initData)];\
});\
});\
return _manager;\
}\
\
+ (instancetype)share##name {\
return [[self alloc] init];\
}\
\
- (id)copyWithZone:(NSZone *)zone {\
return _manager;\
}\
\
- (id)mutableCopyWithZone:(NSZone *)zone {\
return _manager;\
}\
\
- (NSUInteger)retainCount {\
return MAXFLOAT;\
}\
\
- (oneway void)release {}\
\
- (instancetype)retain {\
return _manager;\
}
#endif
#endif /* MZSingleInstance_h */
使用：
// .h
#import <Foundation/Foundation.h>
#import "MZSingleInstance.h"
NS_ASSUME_NONNULL_BEGIN
@interface MZDaoManager : NSObject
MZSingleInstanceH(DaoManager)
@end
NS_ASSUME_NONNULL_END
// .m
#import "MZDaoManager.h"
@implementation MZDaoManager
MZSingleInstanceM(DaoManager)
@end
